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Hard Starts in Cold Weather

HoytBows

HoytBows

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Ex-Michigander, now Elizabeth Colorado
K guys my buddy is starting to have issues with his truck starting. Its an 03 LB7 with about 50k on it. He's had it for awhile and never had much trouble getting it started in really cold weather like -10ish. Even sometimes without plugging it in. But recently it has not been starting up real easy and the temps are not even below 0. He's going to get his batteries tested but beyond that i dont know where to start looking for problems.

The other morning it wouldnt start at like +5 so he waited until it got up to about 35 and it finally fired up. I thought maybe a gell up, but all the fuel thats sold down where he's at is already treated.

What are things he should check on. Most of the time the truck was not plugged in. Do glow plugs go bad? I understand that the trucks dont like the cold weather but its just that the pattern is changing because it used to start just fine in the really really cold and now its struggling when its not that cold.
 
Any codes present? Glow plugs in these can go bad as my 01 had 3 bad ones in it. Also the metal bars that power the glow pugs are known to burn out just after the #8 glow plug which will leave you with only 1 working glow plug if it's a federal emissions truck.
 
Had the batteries checked and they tested ok. When he starts the truck he looses radio and aux fan (heater fan) power. Starts real hard, when its plugged in it starts fine. When I was on the phone with him he told me that he started it multiple times last year in the mountains when it was -15 and it started right up.

I still suspect the batteries and dont trust the test.. any other opinions?
 
For the heck of it he should change the fuel filter. Might be waxed until it gets warmer. He should be using some kind of anti-gel even if the supplier "says" they are. Once you gel up, it can take 2-3 filters to get it cleared up. I know this from personal experience...:mad2:
 
I use power service additive (white bottle) religiously in the winter. It's relatively cheap (costs about $2 a tank) and we've never had a gel problem. I'd try some Diesel 911 in the tank (orange bottle) let it run for a while, then change the filter. Then run the tank down a long ways, and fill it up with at least 50/50 blend, or #1 with Power Service out of the white bottle. My $.02
 
when he starts the truck, does it turn over slower? like when it is colder it turns over slower....I would suspect the batteries too as they can show good when it is warmer.
 
K guys this same problem is rearing its head again this winter. Both batteries are brand new now. He plugs it in when its cold and doesn't get much of a change when he goes to start it up.

Will bad glow plugs throw a code?? If not, how can I test them??

Is there any way to test the block heater to make sure its working, other than the obvious motor temp in the morning being fairly warm?
 
I know my block heater will actually sizzle about minute after you plug it in, so you may want to listen to it to for the sizzling sound. And of course you can put your hand to the block on the passenger side by the motor mount to see if it is warming up after about an hour or so of it being plugged in. As for teh glow plugs, I would get a test light to start with and see if you are getting power to the passenger side ones when somebody turns the key on. Another thing to do is does teh voltage come right up immediately after you start it? If so then I am willing to bet they are not working properly. It will code if the relay fails, but if the bus bar on the drivers side rusts through that will not code. As for testing the glow plugs, you'll have to go through and disconnect both of teh bus bars to isolate the glow plugs from each other. Next take your test light and hook the ground connection up to the positive battery post. Touch the probe end to the terminal on the end of the glow plug. If the test light lights up, then the plug is most likely good, if it doesn't it is bad. this test only applies to federal emissions trucks as the cali emissions trucks are completely different and will code if a single glow plug goes out.
 
I'm not Dmax literate but I would assume if you removed a glow and put power to it, it should turn red.

The block heater should have a sizzling sound while plugged in. You could also reach up and touch the block where it is and feel if it is warm.

You can also use an ohm meter across the plug ends, there should be a resistance. Could also be a bad cord.
 
Glow plugs fail all the time, and is the most probably cause of this issue.

Glow plugs should be very low resistance through them. So if you isolate one, like TheFerm said, then a better test than the test light would be to put a digital multimeter between the plug connector and the body/threading of the glow plug (which is just like connecting the meter lead to the engine when installed).

So isolate the plugs then check for resistance, it should be less than 1 ohm. Anything over a couple ohms and youre not doing good, and an open circuit aka overload on a digitial meter is bad. I have found some that were 100,000 ohms, which is almost an open circuit, but it would still allow the light to go on if using a test light. It just would be dim, so then you would have to determine how dim was the light compared to no resistor in series. Better to just get the resistance check.
 
buddy said:
Glow plugs fail all the time, and is the most probably cause of this issue.
Click to expand...

Glow plugs in a federal emissions DURAMAX do not fail very often(CALI emissions ones do because they get ran for so long all the time due to CALI emissions laws). This is why we need to know which one he has as it makes a difference on how to go about diagnosing it.
 
Good point, in general though are glow plugs like 50K mile maintenance on a Dmax, or 5 years or something like that? Location matter, since they will get used more in the North?
 
I don't know about the LB7 ones or the Calif emissions tune but the LLY and LBZ glows are about bulletproof usually. Many 200+k mile sets w/o a problem.
 
Is that possibly because you also have the intake air heaters, which maybe thats his issue, or isnt there like some huge fuse and relay that controls both of them
 
The grid heater makes all the difference. And yeah, I think its something in the area of 40 amps. When you fire up, the volts drop way off to 12.5-13 or so. The cycle is: WTS, start, grid on, high idle, IAT reaches (whatever it's supposed to... IDK?) X-degrees, TC locks for trans warmup.
I've fired mine on several occasions at -15 to -20 F without any problem other than the backpressure on the trans cooler lines can cause the crappy crimps to leak.
 
Looks like the LB7 has the glows and air heater running on same circuit, same relay and 175 amp fuse. So first thing I would do is check this 175 amp fuse. If thats good suspect the relay. And if both of them are fine, power exits the relay during WTS, then I would check the glow plugs.
 
buddy said:
Looks like the LB7 has the glows and air heater running on same circuit, same relay and 175 amp fuse. So first thing I would do is check this 175 amp fuse. If thats good suspect the relay. And if both of them are fine, power exits the relay during WTS, then I would check the glow plugs.
Click to expand...

The intake heater draws about 45-50 amps, but it only runs after the engine is running from what I can see in the programming. The glow plugs draw about 13-13.5 amps in good shape. There are 2 relays in the glow plug controller, but they are both fused via the 175 amp fuse. If the fuse was popped though, he would have a check engine light with a P0380 code and an intake heater code in it. LB7 and 04.5-05 LLY's use the same basic glow plugs, but they are prett ygood. At 162K on my donor, only 1 had failed but was due to rust from where some water had gotten on it. The CALI emissions trucks use an actual integrated controller for the glow plugs that monitors each one individually. And the wait to start light doesn't neccesarily mean the plugs are on as it is independant of teh glow plug system in the ECM, but most of the time the plugs will stay on longer than the light does. Heres mine starting at 8 degrees, starts the same as summer time.
http://www.youtube.com/watch?v=7KybncEUsN0
 
GPs are fused at 125A on my LBZ. I didn't see what fuse the grid heater was on before I said to hell with it and went in to do other things.
 
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